1. Field of the Invention
The present invention relates to a thin film magnetic head used for recording/reproduction in a magnetic disk storage apparatus, a manufacturing method therefor, and a magnetic disk storage apparatus and disk array system. in which to mount the thin film magnetic head.
2. Description of the Background
Along with an increase in the recording density of magnetic disk storage apparatuses, the coercive force of the recording media has also been increased. A need has been recognized in the art to provide a material having a high saturation magnetic flux density (Bs) that is capable of producing a magnetic field strong enough to write into a high coercive medium for the magnetic core material or writing heads.
Materials having a high saturation magnetic flux density include CoNiFe (Bs>1.7 T) which has a higher Bs than Ni45Fe55 that is currently used as the magnetic core material (Bs: 1.6 T) as described in JP-A-89422/1994, JP-A-241503/1996, JP-A-346202/1994 and JP-A-3489/1995. Further, Japanese Patent Publication No. 2821456 discloses a method of preparing a plated layer with a high Bs using a bath without the addition of saccharine sodium in the plating solution composition.
To attaining a magnetic disk storage apparatus with high recording density, it may be necessary to use a layer forming technique capable of stably forming a magnetic core with an increased thickness for generating a more intense magnetic field. The technique includes the use of a material with a high saturation magnetic flux density (Bs) capable of producing a sufficient magnetic field to write into a high coercive force medium.
As described in Japanese Patent Publication No. 2821456, the Co—Ni—Fe soft magnetic material layer prepared from a bath that does not contain a stress relieving agent has a Bs of at least 1.9 T and a Hch of no more than 2.5 Oe. Because since the stress of the plated layer is large, peeling may ensure in a formed layer with a thickness greater then approximately 2.0 μm, making the layer formation difficult.
Further, as described in JP-A-346202/1994, the soft magnetic Co—Ni—Fe material layer prepared from a bath containing a stress relieving agent may provide a layer with a low coercive force of approximately Hch=0.4 Oe. However, assuming the peak intensities at fcc (111) face, fcc (200) face and bcc (110) face in the X-ray diffraction as I(111), I(200) and I(110), respectively, such a layer could not be obtained unless a substantially face-centered cubic system was formed having a peak intensity ratio of 0.1≦I(200)/I(111)≦0.2 and annealing was applied after the formation of the layer. Further, unevenness may increase in the surface shape of a layer if the layer composition is deviated in a region containing a slight amount of body-centered cubics in the face-centered cubics, which results in clouding and an inability to obtain a gloss layer.
As can be seen from the conventional applications described above, it is difficult to stably mass produce magnetic heads having high saturation magnetic flux density capable of producing sufficient magnetic fields which correspond to a high recording density.